1. Field of the Invention
This invention relates to a horizontal continuous casting method and its device, and particularly to a horizontal continuous casting method and its device suitable for casting a copper alloy.
2. Discussion of the Background
FIG. 5 is a sectional view showing a conventional horizontal continuous casting device for a copper alloy. In FIG. 5, a reference numeral 1 designates a heat-reserving furnace, 2, a molten metal stored in the heat-reserving furnace 1, 3, a heating unit formed in the heat-reserving furnace 1, 4, an electric power heater for heat reservation provided at the heating unit 3, 5, a graphite mold provided at a side face of the heat-reserving furnace 1 in the horizontal direction, 6, a molding space formed in the graphite mold 5, so as to cast a cast block 7 by passing the molten metal 2 therethrough, and 8, a water jacket provided around the graphite mold 5 so that it covers over the peripheral portion thereof.
In the conventional horizontal continuous casting device constructed as above, an inlet for molten metal 9 of the graphite mold 5 is in an open state. The molten metal 2 stored in the heat-reserving furnace 1, enters the casting space 6 of the graphite mold 5 through the inlet for molten metal 9, and the cast block 7 is molded by cooling the molten metal 2 by cooling water passing in the water jacket 8. The continuous casting is performed by extracting the cast block 7 in the horizontal direction. In the heat-reserving furnace 1, the molten metal 2 is maintained at a constant temperature by ON-OFF or repetition of switching of electricity feeding quantity, of the electric power heater for heat reservation 4.
In case of a vertical continuous casting method, casting is performed in a downward flow. Therefore, a method is known wherein a flow-resistant portion is provided at a casting nozzle which connects a tundish and a mold to prevent picking-up of nonmetallic inclusion such as casting powders, thereby decreasing a downward flow rate of the molten metal and accelerating a floating separation of the nonmetallic inclusion (for example Japanese Unexamined Patent Publication No. 130456/1985). In the horizontal continuous casting method, since the nonmetallic inclusion floats up on the surface of the molten metal 2 in the heat-reserving furnace 1, as shown in FIG. 5, no consideration is given thereto.
However, in the conventional horizontal continuous casting method and the device as stated above, since the molten metal 2 in the heat-reserving furnace 1 is maintained at a constant temperature by ON-OFF or switching of the electricity feeding quantity of the electric power heater for heat reservation 4, convection is always caused in the molten metal 2, and a considerable temperature variation is caused in the molten metal just before casting solidification in the graphite mold 5. Accordingly, a thermal stress is generated by a nonuniform temperature distribution generated in the cast block during the casting, whereby casting cracks are caused, or breakout (breakage of cast block) is generated due to insufficient deformation resistance thereof with respect to a change in resistance during the extraction.